1. Field of the Invention:
An arc heater system for operating on line frequency AC power with excellent electrical stability and commercially acceptable performance characteristics as a high energy heat source and operable on a myriad of gases in oxidizing, reducing, or inert conditions.
2. Description of the Prior Art:
As is well known the self-stabilizing arc heater is a single phase device for which the power waveform and the working gas enthalpy level are sinusoidal. The fluctuating enthalpy level is believed to enhance the quenching phenomena in gaseous reactions, such as acetylene production from light hydrocarbons and nitrogen fixation from elemental nitrogen and oxygen, as evidenced by lower measured specific energy requirements compared with other reported constant enthalpy plasma equipment operated on DC power. For example, it has been found that the energy requirements for an AC arc heater plant are as low as 3.7 Kw hr/pound of acetylene produced from methane, whereas an energy requirement of about 4.7 Kw hr/pound of acetylene is reported for a DC arc heater plant.
While the single phase arc heater is beneficial for gaseous reactions, it is detrimental for the heating of solids because when solid particles are injected into the arc heater exit stream during the lower portion of the power wave, they become trapped in a cold gas layer and are therefore not heated to the desired working temperature. An example of where such a phenomena may occur if operating conditions are not properly controlled is a chemical reaction occurring at a high temperature between the arc heated gas and powdered ore injected into the stream for ore reduction as disclosed in U.S. Pat. No. 3,765,870, entitled "Metal Powder Production". Moreover, the single phase device has been objected to because it represents a large unbalanced load in the user's distribution system, which objection may be more or less important depending upon the size and stiffness of individual distribution systems.